Filter elements for filters

Abstract

A filter element has an upstream-side filter layer and a downstream-side filter layer. The downstream-side filter layer is attached to the upstream-side filter layer. The upstream-side filter layer has a coarser mesh than the mesh of the downstream-side filter layer. The upstream-side filter layer has a plurality of through-holes formed therein and extending throughout the thickness of the upstream-side filter layer. The plurality of through-holes allows the filter element to continue to be used when the rest of the upstream-side filter layer is clogged and the downstream-side filter layer still possesses filtering capability.

1 . A filter element for removing dust and contaminants from the air, comprising: 
 an upstream-side filter layer; and    a downstream-side filter layer attached to the upstream-side filter layer,    wherein an upstream-side filter layer mesh is more coarse than a downstream-side filter layer mesh;    wherein the upstream-side filter layer has a plurality of through-holes formed therein and extending throughout the thickness of the upstream-side filter layer.    
   
   
       2 . The filter element as in  claim 1 , 
 wherein an open area of each of the plurality of through-holes has an average diameter within a range of 1 mm to 5 mm; and    wherein a ratio of a cumulative total of the open areas of each of the plurality of through holes to an effective filtration area of the downstream-side filter layer is within a range of approximately 5% to 20%.    
   
   
       3 . The filter element as in  claim 1 , 
 wherein the upstream-side filter layer comprises a non-woven fabric having a weight per unit area within a range of approximately 3 g/m 2  to 20 g/m 2 ; and    wherein the non-woven fabric is made of fibers having an average diameter within a range of approximately 5 μm to 10 μm.    
   
   
       4 . The filter element as in  claim 3 , 
 wherein the downstream-side filter layer comprises a filter paper.    
   
   
       5 . The filter element as in  claim 1 , 
 wherein each of the plurality of through-holes are distributed approximately equidistantly from each other within a plane defining the upstream-side filter layer.    
   
   
       6 . The filter element as in  claim 2 , 
 wherein the downstream-side filter layer comprises a filter paper with filtration pores having an average diameter within a range of approximately 25 μm to 45 μm.    
   
   
       7 . The filter element as in  claim 1 , 
 wherein the upstream-side filter layer and the downstream-side filter layer are directly bonded to each other without any additional bonding agents.    
   
   
       8 . The filter element as in  claim 7 , 
 wherein the upstream-side filter layer comprises a non-woven fabric made of fibers; and    wherein the downstream-side filter layer comprises a filter paper; and    wherein the fibers are formed into the non-woven fabric as the fibers fall directly onto the filter paper.    
   
   
       9 . The filter element as in  claim 8 , 
 wherein the fibers fall in a semi-melted state onto the filter paper, so that the fibers contacting the filter paper are bonded to the filter paper as the fibers solidify.    
   
   
       10 . A filter element for removing dust and contaminants from the air, comprising: 
 an upstream-side filter layer; and    a downstream-side filter layer integrated with the upstream-side filter layer,    wherein the upstream-side filter layer comprises a non-woven fabric having a weight per unit area within a range of approximately 3 g/m 2  to 20 g/m 2 ;    wherein the non-woven fabric is made of fibers having an average diameter within a range of approximately 5 μm to 10 μm;    wherein the upstream-side filter layer has a plurality of through-holes formed therein and extending throughout the thickness of the upstream-side filter layer; and    wherein the downstream-side filter layer has a greater weight per unit area than the upstream-side filter layer.    
   
   
       11 . The filter element as in  claim 10  wherein each of the plurality of through-holes formed in the upstream-side filter layer is defined by an open area, 
 wherein a ratio of a cumulative total of all of the open areas of each of the plurality of through holes to an effective filtration area of the downstream-side filter layer is within a range of approximately 5% to 20%.    
   
   
       12 . The filter element as in  claim 11 , wherein the downstream-side filter layer comprises a filter paper.  
   
   
       13 . The filter element as in  claim 12 , wherein the filter paper of the downstream-side filter layer has a plurality of filtration pores, 
 wherein each of the plurality of filtration pores has an average diameter within a range of approximately 25 μm to 45 μm.    
   
   
       14 . The filter element as in  claim 13 , wherein the upstream-side filter layer is directly formed onto the downstream-side filter layer.  
   
   
       15 . The filter element as in  claim 13 , wherein the filter element further comprises a hot melt sheet, and 
 wherein the upstream-side filter layer is laminated onto the downstream-side filter layer via the hot melt sheet.    
   
   
       16 . The filter element as in  claim 13 , wherein the upstream-side filter layer is embossed onto the downstream-side filter layer.  
   
   
       17 . A filter element for removing dust and contaminants from the air, the filter element allowing ambient air to flow through the filter element and become filtered air, comprising: 
 an upstream-side filter layer permitting the ambient air to enter the filter element;    a downstream-side filter layer permitting the filtered air to leave the filter element;    wherein the upstream-side filter layer comprises a non-woven fabric having a weight per unit area within a range of approximately 3 g/m 2  to 20 g/m 2 ;    wherein the non-woven fabric is made of fibers having an average diameter within a range of approximately 5 μm to 10 μm;    wherein the downstream-side filter layer has a greater weight per unit area than the upstream-side filter layer;    wherein the upstream-side filter layer has a plurality of through-holes formed therein and extending throughout the thickness of the upstream-side filter layer; and    wherein each of the plurality of through-holes formed in the upstream-side filter layer is defined by an open area; and    wherein a ratio of a cumulative total of all of the open areas of each of the plurality of through holes to an effective filtration area of the downstream-side filter layer is within a range of approximately 5% to 20%    
   
   
       18 . The filter element of  claim 17 , wherein the downstream-side filter layer comprises a filter paper.  
   
   
       19 . The filter element of  claim 17 , wherein the upstream-side filter layer is bonded to the downstream-side filter layer.  
   
   
       20 . The filter element of  claim 17 , wherein each of the plurality of through holes is approximately spaced equidistantly from one another.